Software Architecture

The low level controller in the Variations Too project is an Arduino, beloved by LED Flashers around the world. But my last actual job title in the Software Industrial Complex was Extensibility Architect (...see how well that went here...) so I can't leave things alone without extending upon them. And the Arduino system is badly in need of some Software Architecture. Since it's simple enough, in most respects, that I can almost understand it, that's what I've been doing by fits and starts lately.

First, there's a lot of busy-waiting going on. The Analog to Digital Converter (ADC) code just starts a conversion and sits there waiting for it to complete. This is not so bad as it usually comes through in a tenth of a millisecond, but that's about 400 instruction cycles that could be used for doing something useful.

Then... delay() is the favored way to make something happen sometime in the future. This is just a bad idea in a system that might be responding to a buncha stuff in a realish time frame.

And. Then. Speaking of responding. The "usual" way to do responsible data acquisition is to sample at some fixed rate. There is no provision for doing that in the system as it is constructed.

Plus. Communication. One often wants to send and receive messages from the rest of the computing planet in some reliable manner. Unfortunately the Serial interface has hidden it's underlying structure and parsing mechanisms such that this is difficult. Doubly impossible if one needs to implement a message format that contains framing, headers, and/or checksums, which might, for instance, be of use in less than predictable mediums like radio.

On the other hand

I was making amazing claims about the Arduino system, such as, "It just seems to work!" -- in comparison to a previous ATmega based development system, constructed by grad students that needed thesis topics, I used, lets just say, 20 years ago, where my strongly held belief was that NO ONE knew how the build system worked, such that the way to get it running was to reinstall different versions until a compile stuck to the wall. But. Of course. The one time I tried to teach a class using Arduinos, three of the six students had varying levels of failure, from port configuration (on a Mac, so, well, yeah, sure...) to execution failure (on what appeared to be a garden variety Widows machine). So I've forsworn further involvement of that nature.

But I woolgather...

Here's the latest bolus of my improvements to the world:

http://www.etantdonnes.com/DATA/schipArduino.zip

Details at 11.